European Central Bank, Frankfurt. Prominent German figures have challenged decisions such as the euro bailout and use of a single currency. Photograph: Alamy

It was a cold day in 1998 when four men went by foot to the German constitutional court in the city of Karlsruhe to rescue the Deutschmark. Their bid failed – but a standard operating procedure for German Euroscepticism was born.

Since then, Germany's pre-eminent court has been repeatedly petitioned by a mix of lawyers, economists and financial experts alarmed at the gathering pace of European integration. Their judgments have been nuanced. Apart from a half-victory for the eurosceptics in 2009, the judges have generally ruled against the petitioners. But their rulings have made it clear that they expect European integration to be properly democratic, sanctioned by the "clear will of the German people".

Among those early complainants in 1998 were Joachim Starbatty, professor of political economics at Tübingen University, and Karl Albrecht Schachtschneider, a law professor from Erlangen. In their briefcase they had a 352-page writ railing against the introduction of a common European currency.

Less than three months later they were sent packing. The constitutional court in Karlsruhe didn't want to stand in the way of the common currency. Nevertheless, the seeds of an anti-euro cell were sown – a cell which was set to criticise ever more sharply the European policy of the federal government. Their favoured weapon: bringing lawsuits in Karlsruhe.

Schachtschneider had form on this front. As early as 1993 he had already fought against the Maastricht treaty in the highest court in Germany. He didn't win. But the judgment from Karlsruhe was set to cause serious headaches for the German government further down the line, raising an important question: would the constitutional court one day stop the train hurtling towards European integration?

Though the judges rejected Schachtschneider's claim, they issued in their judgment a reminder that the European unification process should be anchored in democracy. They also reserved the right to have the final say on European matters, bequeathing German citizens an extremely generous right to go to court on EU matters.

The Euro-rebels saw this as an invitation. When the EU was trying to take the next step towards integration with the Lisbon treaty in 2009, these men brought another case to Karlsruhe. This time with a different lineup. Starbatty was still there, but at his side was now Dieter Spethmann, another representative of the old West Germany – he was head of the steel company Thyssen. With them was Franz Schenk Graf von Stauffenberg, the son of the resistance fighter who was shot by the Nazis after plotting to kill Hitler in 1944.

The lawyer among them, the ever resourceful Markus C Kerber, probably came up with the abstruse idea of supporting their case by quoting the right to resistance. But it was arguments advanced by a certain Peter Gauweiler who gave the court pause for thought.

A master populist, this politician had carved out a name for himself as a maverick in the CSU, the Bavarian sister party to Angela Merkel's Christian Democrats, and had made EU scepticism his party piece. He found a congenial partner in the Freiburg lawyer Dietrich Murswiek. It was his contribution which brought a half-victory for the Euro-sceptics in the judgment on the Lisbon treaty in 2009. The national parliament was again given the right to have its say, but above all, the court drew a line in the sand marking the boundaries of European integration, which could only be crossed with the "clear will of the German people".

Two years later, in 2011, the rebels found themselves once again in Karlsruhe, this time bringing a case against the euro bailout. In this judgment, the court said that the budgetary decision-making must remain democratically anchored – which meant the Bundestag would always retain the last word on questions of gigantic financial liabilities. Here, once again, it was Murswiek who enjoyed the most attention from the judges.

One can ascertain from the Karlsruhe judgments a reticence towards the desire for brisk integration that reigns in Brussels.

Ultimately, the judgments combine to make a particularly peculiar melange: among the plaintiffs there is a mix of economic pessimism and insecure nationalism with a shot of nostalgia for the Deutschmark.

In the court itself, the worry dominates that democracy could be diluted into nothing in Europe. This concern is genuine and is no doubt bundled up with another fear: that the Karlsruhe court would have even less of a say, the further the integration progresses.

In 2011, the Guardian teamed up with five other papers from the largest EU countries to investigate the European predicament and seek to tease out solutions. In the three years since the Europa team – the Guardian, Le Monde, El País, La Stampa, Gazeta Wyborcza and Süddeutsche Zeitung – have worked together to dig deeper into some of the major issues of the day: economic decline, migration, unemployment, mental illness, European elections and the deepening disaffection for the European Union itself.